The invention concerns a napkin folding device as well as components thereof.
There are known devices for the folding of cloths, such as towels. Patent specification U.S. Pat. No. 2,025,246, for example, describes a folding device equipped with a folding unit for the folding of individual towels, a storage unit for holding folded towels from the folding unit, a delivery unit for the holding out of unfolded towels and a transport unit for the feeding of the unfolded towels from the delivery unit to the folding unit. In the delivery unit the unfolded towels are held in a stack. A grip system of the transport unit removes individual towels one by one from this stack to feed them to the feeding unit.
From patent specification U.S. Pat. No. 1,371,349, a napkin folding device is known which comprises a folding unit for the folding of individual napkins, equipped with a storage unit for holding folded napkins from the folding unit. An individual unfolded napkin is manually fed to the folding unit. In the folding unit, the individual napkin is folded in a double walled housing body and from there fed to the storage unit by means of rollers.
From patent specification U.S. Pat. No. 4,865,579, a napkin folding device is known which comprises a folding unit for the folding of individual napkins. The folding unit contains multiple folding devices for multiple folding of an individual napkin, whereby the folding devices are employed one after another. Each folding device folds the individual napkin along a prescribed axis.
From patent specification US JP 07275600, a napkin folding device is known, the folding unit of which works in a zigzag to fold individual napkins. Here, the napkin is placed on a holding table with recesses. To fold in zigzag form, the napkin is pushed from the folding unit into the recesses.
It is desirable to specify a napkin folding device that provides for a significant improvement in the folding of napkins. Likewise, components for this device must be created.
The napkin folding device according to an aspect of the invention features a delivery unit that has a magazine for holding out unfolded napkins with at least two delivery levels. In this connection, the term “unit” designates an entire unit, which can consist of or comprise multiple individual units. In this way, it is possible to simply load the delivery unit with large quantities of unfolded napkins and to simply remove the napkins, which results in a significant savings of time in the folding of napkins. This also advantageously leads to a significant improvement in the folding of napkins, because the folding operation can proceed almost automatically. It requires far fewer manual activities, such as loading the delivery unit with unfolded napkins or removing folded napkins from the storage unit, inasmuch as these activities take place at greater intervals of time.
Advantageously, the delivery unit is located in at least one delivery level in a loading position and in at least one delivery level in a removal position. This way the loading of the delivery unit and the removal of an unfolded napkin for the subsequent folding operation can take place simultaneously, which results in a considerable savings of time.
Preferably, the delivery unit has a magazine that is run along a feed path in a circular direction so it can be filled with unfolded napkins. In an alternative embodiment, the delivery unit has a magazine that can rotate around a vertical axis and/or be driven along an axis so it can be filled with unfolded napkins. In this way, it is possible to load the delivery unit with large quantities of unfolded napkins, which results in a considerable savings of time in the folding of napkins. It is thus possible to operate the napkin folding device over a longer period of time without manual intervention.
Expediently, the magazine has multiple shelves disposed above each other, whereby each shelf is stored in guide rails in the delivery unit. In an alternative embodiment, the magazine has at least two units disposed side by side, each with multiple shelves disposed above each other. As a rule, a large stack of unfolded napkins will sag in the middle. Because the magazine, or the magazine units, has multiple shelves, which are each loaded with smaller stacks of napkins, the magazine can advantageously be loaded with large quantities of unfolded napkins without creating the danger of sagging in the napkin stacks.
In a further embodiment, in order to drive the magazine containing the guide rails and the shelves in the circular direction, the delivery unit has a first handling device, which drives the guide rails in the delivery unit, and a second handling device, which drives the shelves in the delivery unit. This yields a space-saving and secure alternative for driving the magazine in the delivery unit. The secure motion of the magazine makes the uninterrupted delivery of napkins to the folding unit possible. Preferably, the delivery unit is constructed in such a way that automatically after each cycle, for example, after provision and delivery of napkins to the folding unit, it places the napkin stack in such a way, for example, pushed upward, that the upper napkins remain always at the same height, and correct removal by means of a carrier framework or a similar system can be performed. The pushing up can be accomplished by means of a spring system, which is pushed down by the dead weight of the napkin stack and remains always taut. As each napkin is taken from the stack, the napkin stack is successively moved upward. The pushing up or placing can, however be carried out with other means, e.g., an electric or pneumatic handler or similar means.
Advantageously, at least one part of the shelves of the units of the magazine opens on hinges along the vertical axis. This enables simple feeding of the delivery unit with large quantities of unfolded napkins and simple removal of the napkins, which results in a considerable savings of time in the folding of napkins.
Preferably, the transport unit has vacuum handling unit and a folding stage disposed above it along a vertical axis. In an alternative embodiment, the transport unit has a grip unit and a folding stage. Advantageously, this enables a secure and careful transport of unfolded napkins to the folding unit of the napkin folding device. In particular, the transport unit allows the napkins to make short trips to the folding unit, which saves both construction space and costs.
In a further embodiment, the transport unit is movably mounted on the housing of the napkin folding device along at least two axes. This way the transport unit can be moved selectively either downwards to one of the napkins disposed on the highest shelf of the delivery unit to remove the napkin from the shelf or upward from one of the napkin stacks lying on the shelf to lift the napkin from the napkin stack.
In a further embodiment, the vacuum handling unit is operatively connected to the folding stage unit by means of a separation unit. Advantageously, the napkin is in this way quickly and carefully separated from the vacuum handling unit and transported out to the folding stage unit.
Preferably, the folding unit has a robotic grip system. Advantageously, the grip system is designed in such a way that even complicated napkin forms are automatically producible. Alternatively or additionally, a corresponding tilting mechanism can be provided.
It is especially preferred to design the folding stage unit as a table, which is provided with a friction lining and/or a vacuum device and/or a separation device and/or a holding down device. Advantageously, the table serves not only to hold unfolded napkins, but also to accommodate and integrate fixing devices and separation devices. With a fixing device, a napkin can be fixed during folding, to prevent the napkin from slipping during the folding process. With a separation device, if necessary for one napkin, layers lying one on top of the other of the napkin being processed can be separated for appropriate crease patterns, in order, for example, to lift one layer and execute a folding movement with it.
Expediently, the table and/or the folding unit and/or the grip unit are designed as rotatable, preferably around a vertical axis. Advantageously, that way the table and/or the folding unit and/or the grip unit are freely adjustable.
The grip system preferably operates the folding unit together with the finger grip system of the transport unit. The finger grip system of the transport unit thereby functions as a supporting complement to the grip system of the folding unit.
A further preferred embodiment of the invention provides that the storage unit according to the invention be designed according to the paternoster principle. For this, the storage unit has two shafts in which cartridges for holding folded napkins are operated in a controlled circular operation. Through this means, it is possible to shelve large quantities of folded napkins. An emptying of the storage unit is necessary only at large intervals of time, which results in a considerable savings of time during napkin folding. Operation of the napkin folding device is therefore possible for a longer time without manual intervention. However, it is also conceivable to release folded napkins onto a conveyor belt. In this way, for example, a filled cartridge can be released onto the conveyor belt. It is just as possible to release individual folded napkins.
It is especially preferred that the napkin folding device has an inspection unit that is provided to identify deviating values. Advantageously, the inspection unit identifies primarily the layer of the respective napkin, and additionally, certain defined problems, such as tolerances and dirt. The inspection unit can consist of or comprise one or multiple pieces of optical equipment, such as cameras. Should a problem be identified such as an incorrectly placed napkin or dirt, an alarm signal may be given. If necessary, the folding process can be interrupted. Image recognition techniques may be used to identify problems.
A delivery unit for a napkin folding device is further proposed, which is configured to work together with one or multiple components of the napkin folding device according to the invention. Preferably, the delivery unit can store unfolded napkins and provide a transport unit. Preferably, the delivery unit can contain a magazine driven along a feed path in a circular direction so that it can be filled with unfolded napkins.
A transport unit for a napkin folding device is proposed, which is configured to work together with one or multiple components of the napkin folding device according to the invention. Preferably, it can include a vacuum handling unit and a folding stage disposed above it along a vertical axis. The transport unit can preferably work together with a delivery unit and carry away unfolded napkins from it and/or work together with a folding unit to deliver the unfolded napkins to it.
Further, a folding unit for a napkin folding device is proposed, which is configured to work together with one or multiple components of the napkin folding device according to the invention. Preferably, it can include a robotic grip system with which the napkins can be reproducibly automatically folded. The controls can provide a multiplicity of drive processes of the grip system, so that the desired forms are easily selectable and producible. Preferably, the folding unit can work together with a transport unit that feeds in unfolded napkins and/or removes and/or works together with a storage unit in which folded napkins can be collected and stored.
Further, a storage unit for a napkin folding device is proposed, which is configured to work together with one or multiple components of the napkin folding device according to the invention. Preferably, it can have a design according to the paternoster principle. Preferably, two shafts can be provided, in which cartridges for holding folded napkins are drivable in a controlled circular operation. The storage unit can preferably work together with a folding unit and/or a transport unit and pick up the folded napkins.
In the following figures, functionally similar working elements are designated with the same reference numbers.